Magnetic circuit control for burglar alarms



June 17, 1952 B. SCHENENDORF 2,600,581

MAGNETIC CIRCUIT CONTROL FOR BURGLAR ALARMS Filed July 19, 1949 2 SHEETS-SHEET l 1 7 1 J fig Z 14 1 1 INVENTOR.

L @MA g e 17 TT'OR/TE Y- June .17, 1952 B. SCHENENDORF MAGNETIC CIRCUIT CONTROL FOR BURGLAR ALARMS Filed July 19, 1949 2 SHEETSSHEET 2 I N V EN TOR.

HT T01? E Y Patented June 17, 1952 MAGNETIC CIRCUIT CONTROL FOR BURGLAR ALARMS Benjamin Schenendorf, Brooklyn, N. Y.

Application July 19, 1949, Serial No. 105,513

The purpose of my invention is to provide an activator for a burglar alarm system whereby -I employ a magnet housed within a box secured to the frame of a door, which by means of movement of a certain lever to which the magnet is attached activates a micro-switch by contact with another magnet set N to N and S to S poles which is secured within a box on the door, said circuit being opened to set the alarm when the door is opened and the lines of force of the two magnets are broken.

A further object of my invention is to provide a device adapted to control electrical circuits by means of the repelling action of magnets.

My device as an alarm activator, is used on wooden or transparent doors, for store fronts, revolving doors, garage doors, fire connecting doors, elevator doors, and movable windows.

Referring to the drawing for purposes of illustration:

Figure 1 is a front elevation of a transparent door and frame illustrating the burglar alarm contact device in attached position.

Figure 2 is a section taken on the line 22 of Fig. 1.

Figure 3 is a section taken on the line 33 of Fig. 1 with an auxiliary arm.

Figure 4 is a section taken on the line 4-4 of Fig. 6 illustrating alarm mechanism.

Figure 5 is a section taken on the line 5--5 of Fig. 6.

Figure 6 is a section taken on the line 6-6 of Fig. 4.

Figure '7 is a diagrammatic illustration of the alarm mechanism showing a certain movement when the alarm circuit is manually in a closed position.

Figure 8 is a similar view to Fig. 7 showing a further movement when gravity disconnects automatically.

Figure 9 is a similar view to Figures 7 and 8 showing a still further movement of the circuit automatically disconnected due to the internal magnet being disconnected from the auxiliary magnet.

Referring specifically to the drawings a glass door or plastic door I, mounted in the frame 2 by the pivots 3 on the hinges 4, the upper hinge plate having secured to it a bracket 5 which extends with an arm 6, the extremity of which has secured to it a small box 1. The said box 1 houses a magnet 8, secured by the screws 9.

The poles of the auxiliary magnet extend upwardly to face the poles of the internal magnet 10 which is held either by a strap H to a lever 1 Claim. (Cl. 200--87) 12 or the magnet 10 is soldered to the lever I2, of a conventional micro-switch l3, the said lever being pivoted at M. The micro-switch I3 is held by the bolt Hi to the base It, the cover I1 is secured to both sides of the plates [9 by the screws 20. A projecting pin 2| pivoted to the base wall 16 terminates in a finger knob 22 which extends through a hole 23 in the cover 18. An arm 24 is screwed into the shank of the pin 2| and normally rests against the lower surface of the cover IS. A further cam pin 25 is secured to the pin 2| at a given angle to the arm 24 which works against the surface of the lever 12 when the projecting pin 2| is turned clockwise manually and comes to a stop against stop 24. The micro-switch i3 is provided with three terminals 26a, 26b and 260 for the connection of wiring to a conventional alarm signal mechanism (not shown). Terminals 26a and 261) are adapted to be utilized when a closed circuit is desired through switch l3 while the door is in closed position. Terminals 26b and 260 are adapted to be utilized when an open circuit is desired through said switch with the door in the aforesaid position. Therefore this device is a combination to be used for closed circuit operation or open circuit operation.

The complete box cover I! is secured to the frame 2 by the screws 21 so that the two magnets will be directly in line with one another. The poles of the magnet are set so that N of one magnet is opposite N of the other magnet thus giving a repellent action between the two magnets which in turn controls the circuit on and off.

When it is desired to set the burglar alarm system when closing the premises, open the door and While opened, turn the projecting pin 2| clockwise to a stop 24'. In the position of pin 2| shown in Figure '7 the switch is actuated, allowing the alarm signal mechanism to be set. The door is then closed bringing the magnet 8 under the magnet l 0. This will tend to repel the magnets still further apart and the pin arm 24 will fall by gravity to position shown in Fig. 8 still leaving the circuit closed. When the door is again opened by a burglar or accident, the magnet 8 will be drawn away from under the magnet It], thus allowing the micro-switch contacts to be opened instantly and causing the signal mechanism to operate and activate the alarm signal mechanism. This describes the action on the alarm by my device.

Although the drawing and specification disclose the best use embodied in my invention, I

3 do not desire to be limited to the details of my disclosure as slight changes may be made in the practical adaptation of my invention without departing from the spirit of the invention within the broad scope of the appended claim.

What I claim as new and novel is:

An activating device for a burglar alarm system comprising a housing, a switch having a normal and an actuated position mounted within said housing, a lever secured to said switch and adapted to move said switch from said normal to said actuated position, a first bi-polar magnet carried by said lever and adapted to depress it to thereby retain said switch in normal position, a pin pivotally mounted in said housing, a radially extending cam carried by said pin and adapted to be pivoted into abutment with said lever to raise it from normal to switch actuated position, a radially extending arm carried by said pin adapted to restore said pin to its original position upon the release of said cam from abutment with said lever, a second bi-polar magnet adapted to be positioned in confronting relation with the similar poles of said first magnet to thereby repel said first magnet and raise said lever from abutment with said cam whereby said lever is maintained in raised position solely by means of the repelling force of said magnets.

BENJAMIN SCHENENDORF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,287,896 Crane Dec. 17, 1918 2,384,948 McLaughlin Sept. 18, 1945 FOREIGN PATENTS Number Country Date 9,805 Great Britain of 1893 

